Natural plant fibre reinforced concrete

ABSTRACT

A composite material and process for forming composite material. The composite material comprises a quantity of plastinated plant distributed within a matrix material. The process comprises separating a plant material into plant fibers plastinating the plant fibers and combining the plastinated plant fibers with a matrix material. The plant fibers may be selected form the group consisting of bamboo, hemp and flax. The plant fibers may be formed by crushing a portion of a plant. The matrix material may comprise Polyethylene Terephthalate (PET). The PET may be shredded and heated. The heated composite material may be formed into rebar and be arranged in a pattern within a concrete slurry.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/578,106 filed Oct. 27, 2017 entitled Natural Plant FibreReinforced Concrete.

BACKGROUND OF THE INVENTION 1. Field of Invention

The present invention relates generally to reinforcing bar (rebar) forconcrete and more particularly to rebar formed using a plastinatednatural plant fiber.

2. Description of Related Art

Concrete is a composite material used extensively in construction.Aggregate is mixed with a fluid cement to form a concrete slurry whichmay be poured or molded into a desired shape then hardens over time. Onits own, concrete has high compressive strength but low tensile strengthproperties. As such, concrete is typically reinforced with materialshaving high tensile strength properties to produce a reinforcedcomposite material that has both high compressive and tensile strengthproperties.

Traditionally, steel rebar is used to reinforce concrete. Other methodsof tensile reinforcement include, but are not limited to, steel fibers,glass fibers or plastic fibers. A disadvantage of steel products is thatthey are subject to corrosion over time. Additionally, thesereinforcement products may be difficult or cost prohibitive to source insome markets.

Some natural materials have been tested as reinforcement materialswithin concrete. Examples of such materials include plant fibers such asbamboo, hemp and other poly plastic fibers. A disadvantage of usingbamboo and other natural plant products is that there is a concern forwater absorption into the plant material. With increased water content,the plant can expand causing cracks and voids within the concrete. Driedplant fibers tend to absorb moisture from the concrete, creating a voidwhich defeats the purpose of the reinforcing material. Additionally, anuntreated natural plant can deteriorate over time due to moisture, moldand insect activity. Current treatments in curing bamboo and other plantfibers do not overcome all concerns, such as maintaining physical andchemical properties of the bamboo or other fiber.

SUMMARY OF THE INVENTION

According to a first embodiment of the present invention there isdisclosed a process for forming a composite material comprisingseparating a plant material into plant fibers plastinating the plantfibers and combining the plastinated plant fibers with a matrixmaterial.

The plant fibers may be selected form the group consisting of bamboo,hemp and flax. The plant fibers may be formed by crushing a portion of aplant.

The matrix material may comprise Polyethylene Terephthalate (PET). ThePET may be shredded and heated.

The heated composite material may be formed into the elongate rods withan extruder. The elongate rods may be formed with a surface texturethereon.

The elongate rods may be coated with at least one of recycled concrete,sand or lime to improve adherence of the elongate rods to a concreteslurry. The elongate rods may be arranged in a pattern within a concreteslurry.

According to a further embodiment of the present invention there isdisclosed a composite material comprising a quantity of plastinatedplant distributed within a matrix material.

The plant fibers may be selected form the group consisting of bamboo,hemp and flax. The plant fibers may be formed by crushing a portion of aplant.

The matrix material may comprise Polyethylene Terephthalate (PET). ThePET may be shredded and heated.

The heated composite material may be formed into the elongate rods withan extruder. The elongate rods may be formed with a surface texturethereon. The elongate rods may be coated with at least one of recycledconcrete, sand or lime to improve adherence of said elongate rods to aconcrete slurry. The elongate rods may be arranged in a pattern within aconcrete slurry.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention whereinsimilar characters of reference denote corresponding parts in each view,

FIG. 1 is a flow chart depicting a process for plastinating naturalplant fibers.

FIG. 2 is a flow chart depicting a process for preparing elongate rodswith palatinate natural plant fibers according to a first embodiment ofthe present invention.

FIG. 3 is a perspective view of a composite concrete body havingelongate rods formed of plastinated natural plant fibers therein.

FIG. 4 is a cross sectional view of an apparatus for extruding theelongate rods with plastinated natural plant fibers in accordance withthe method of FIG. 2.

DETAILED DESCRIPTION

The present invention provides a process for forming a reinforced bar(rebar) with plastinated natural plant fibers for use in concrete.According to a first embodiment of the present invention, plant fibersare plastinated by means as are commonly known, then the plastinatedfibrers are combined with a plastic matrix and extruded to form elongaterods to be used as rebar within concrete, as is commonly known.Optionally, the plastinated fibers may be located within a concreteslurry to form a fiber-reinforced concrete mixture, increasing thestructural integrity of the concrete.

Referring to FIG. 1, a process for plastinating natural plant fibers isillustrated generally at 10. Various plastination processes are commonlyknown, and described herein is one exemplary method. It will beappreciated that other plastination methods and techniques may also beuseful as well. The plant fibers may be selected from a desired plantspecies, such as, by way of non-limiting example, bamboo, hemp and flax,although other plant species may be useful, as well. In particular, thebamboo species “Guadua angustifolia”, has been found to have a highertensile strength and may be particularly useful for the present methods.

The plant is harvested and prepared for plastination in step 12. Theplant is dried, crushed and cut to prepare it into individual fibers orgroups of fibres at this stage, although it will be appreciated that theplant may be crushed or cut into individual fibres following theplastination process, as well, such as, by way of non-limiting example,chipping shredding or the like. The plant fibers are immersed in a 100%acetone bath in step 14, which is brought to a temperature of between−13 and 77 degrees Fahrenheit (−25 and 25 degrees Celsius) at whichpoint the acetone replaces the water within the plant cells, thusdehydrating the plant material and eliminating moisture and moldconcerns. In particular, it has been found that room temperature, suchas, by way of non-limiting example, between 59 and 77 degrees Fahrenheit(15 and 25 degrees Celsius has been useful. The plant fibers remain inthe acetone bath until they are saturated with acetone. Followingdehydration, the dehydrated plant material is immersed in a liquidpolymer bath in step 16. The liquid polymer bath may be formed of suchas, by way of non-limiting example, silicone polymer (such a mixture ofBiodur S10 and Biodur S3), polyester or epoxy resin, although otherliquid polymers may be useful, as well. In particular, it has been foundthat a mixture of 100 parts S10 to 1 part S3 has been useful. The liquidpolymer bath with the dehydrated plant material therein may be placedunder vacuum, which vaporizes the acetone in the cells and draws theliquid polymer therein to replace the acetone. Step 16 continues untilsurface bubbles stop forming, at which point the vacuum is released andBiodur S6 is sprayed onto the fibers. Finally, in step 18 the plantmaterial is removed from the liquid polymer bath and the liquid polymerwithin the cells may be cured to a hardened state. The curing processmay include such as, by way of non-limiting example, drying at roomtemperature or applying heat, gas or ultraviolet light.

At this stage, the plastinated fibers 54 may be combined with a concreteslurry to produce a fiber-reinforced concrete product. Concrete withfibrous material therein has been shown to have improved structuralintegrity, helping to control cracking and providing greater impact,abrasion and shatter-resistance. As the water content of the plantfibers has been replaced by a liquid polymer, the fibers will not decay,attract insects or expand due to moisture absorption. Such fibers may beutilized within a matrix of another material, such as by way of nonlimiting example plastics or concrete as described herein and may alsobe utilized as a non decaying fiber which may be used in place of anyother commonly known fibers. In particular it will be appreciated thatsuch plastinated fibers may be stronger than the unplastinated fibers aswell as being resistant to moisture, mildew and rot due to near 0%moisture in such plastinated fibers. Such fibers may also be lesssubject to deterioration when exposed to ultra violet light. By way ofnon-limiting example such plastinated fibers may be useful as asubstitute for organic or inorganic fibers in composite material. Itwill also be appreciated the whole plant or any portion thereof such as,by way of non-limiting example, dimensioned lumber may be plastinated inthe above manner to provide the above advantages. It has also been foundthat including plastinated fibers within other composite materials suchas fiberglass may provide improved impact and noise dampeningproperties.

Turning now to FIG. 2, a process for preparing plastinated plant fiberrods is illustrated generally at 20. Plastic material 56 such as, by wayof non-limiting example, Polyethylene Terephthalate (PET) plastic, suchas from reclaimed water, soda and juice bottles, is washed and shreddedin step 22. The washing and shredding process may be performed on siteor locally available PET plastic facilities may be used, providing localemployment and an incentive for environmental reclamation by removal ofdiscarded PET plastic. The PET plastic material 56 may be shredded byany known means, such as, by way of non-limiting example, through ashredder, grinder, wood chipper, pelletizer or the like. The plastinatedfibers prepared in the process 10 are then combined with the preparedPET plastic in step 24 and fed into an extrusion machine as illustratedin FIG. 4 and further described below. The combined material is broughtto a temperature in the range of such as, by way of non-limitingexample, 475 to 536 degrees Fahrenheit (246 to 280 degrees Celsius) andextruded into elongate rods 50 in step 26. The combined material is keptwithin this temperature range for up to 20 seconds prior to beingextruded. Upon exit from the extrusion machine, while the elongate rods50 are at an elevated temperature in the range such as, by way ofnon-limiting example, 86 to 275 Fahrenheit (30 to 135 Celsius), they mayhave adhesion agent 52 applied thereto while a ribbing surface textureis imprinted thereon in step 28. The adhesion agent 52 may be such as,by way of non-limiting example, lime, recycled concrete or sand,although other adhesion agents may be useful as well. The combination ofa ribbed surface, as is commonly known, and the embedded adhesion agentimproves adhesion to concrete over conventional methods.

The prepared elongate rods 50 may now be used for concrete reinforcementin the same manner as typical rebar is used, as is commonly known asillustrated in FIG. 3 by embedding within or otherwise forming aconcrete structure 40 therearound according to known methods.

Turning now to FIG. 4, an exemplary extrusion apparatus is illustratedgenerally at 60. The extrusion apparatus includes a hopper 62 adapted toreceive the plastinated natural plant fibres 54 and PET plastic material56. The extrusion apparatus 60 may include an auger 64 having aspiralled driving surface or fin 66 extending therefrom such thatrotation of the auger 64 by a motor 68 will move the plastinated naturalplant fibres 54 and PET plastic material 56 along the extrusion housingtowards and through an extrusion die 72. A heater 70 may be provided toincrease the temperature of the combined plastinated natural plantfibres 54 and PET plastic material 56 to the desired temperature. Uponexit from the extrusion apparatus 60, the elongate rod 50 may have anadhesion agent 52 applied thereto, as described above. It will beappreciated that although a single screw style extrusion machine isillustrated, any other suitable extrusion machine may also be usefulsuch as, by way of non-limiting example, a twin screw design. It will beappreciated that the hopper 62 may receive PET plastic material 56without the addition of plastinated natural fibres 54 to form anelongate rod 50 which does not include plastinated natural fibres 54therein, or the hopper may receive PET plastic material 56 with theaddition of alternate fibrous material, such as, by way of non-limitingexample, glass, carbon, aramid or boron fibers.

While specific embodiments of the invention have been described andillustrated, such embodiments should be considered illustrative of theinvention only and not as limiting the invention as construed inaccordance with the accompanying claims.

What is claimed is:
 1. A process for forming a composite materialcomprising: separating a plant material into plant fibers; plastinatingsaid plant fibers by: saturating said plant fibers in acetone todehydrate said plant fibres; immersing said dehydrated plant fibres in aliquid polymer; and subjecting said immersed plant fibres to a vacuum toreplace acetone in said plant fibers with said liquid polymer; andcombining said plastinated plant fibers with a matrix material.
 2. Theprocess of claim 1 wherein said plant fibers are selected form the groupconsisting of bamboo, hemp and flax.
 3. The process of claim 1 whereinsaid plant fibers are formed by crushing a portion of a plant.
 4. Theprocess of claim 1 wherein said matrix material comprises plastic. 5.The process of claim 4 wherein said matrix material is shredded andheated.
 6. The process of claim 5 wherein said heated composite materialis formed into elongate rods with an extruder.
 7. The process of claim 6wherein said elongate rods are formed with a surface texture thereon. 8.The process of claim 1 wherein said elongate rods are coated with atleast one of recycled concrete, sand or lime to improve adherence ofsaid elongate rods to a concrete slurry.
 9. The process of claim 1wherein said elongate rods are arranged in a pattern within a concreteslurry.